Spwig v1.7.4

Admin refinements and reliability fixes on top of 1.7.3. Drop-in — no migrations.

Added

• Responsive image srcset ladders in image_sources for headless storefronts (additive).
• Tabbed admin editors for product reviews and subscription plans.

Fixed

• Page Builder: storefront element CSS (carousel/testimonials/CTA), Add-Page 500, per-release element-registry cache key.
• Selected theme CSS always loads, even mid-switch.

Security

• Review-comment XSS escaping; hardening across email, SMS, and webhooks.